Method and device for cleaning welding torches

ABSTRACT

The invention relates to a method and a device for cleaning welding torches, for example in automated welding lines, on welding robots and in made-to-order production, by means of a cold medium, preferably CO 2  dry ice. According to the method, a compressed air stream, charged with CO 2  dry ice directed constantly or at intervals by a jet nozzle onto one side of the surface to be cleaned and simultaneously describes a rotational movement.

[0001] The invention relates to a method and a device for cleaningwelding torches in automatic welding lines, on welding robots andhand-held devices used in fabrication of pieces tailored to specificneeds.

[0002] There are known several methods for cleaning welding torches. Allthese methods employ mechanical means of cleaning, using one or morewire brushes, several milling cutters or form cutters.

[0003] The disadvantage with such approach is that only the externalarea and part of the internal area can be cleaned by such kind of tools.Smoke gas deposits are not removed completely from inside the torch,neither the anti-stick agents blown-in are.

[0004] Also, the circular layout of the torch selected due to thenecessary rotation of the tools proved disadvantageous as it is anobstacle to the required adaptation of the torch's shape for the actualseam or spot area layout. Any modification in the torch's shape wouldentail a change of the cleaning appliance.

[0005] Another disadvantage is that the originally smooth and mostlynickel-plated surface of the torch undergoes a denudation and becomesrough due to its mechanical processing, which in turn causes an evenfaster and more intense dirtying of torch.

[0006] The invention described in the claims 1 to 3 is based on theproblem of creating both a method and a device for uniform cleaningwelding torches.

[0007] According to claim 1, the problem is solved by a method forcleaning welding torches, for example in automatic fabrication lines,using a cold mixture of abrasives preferably comprising CO₂ pellets pluscompressed air or carbon dioxide snow plus compressed air which is blownuniformly or at intervals against the surface to be cleaned.

[0008] According to claims 4 and 5, the device used for implementing thesaid method is made up of one or more revolving jet nozzles that are toclean a pre-defined section of the welding torch at a certain angle (tobe selected) and the outlet opening of which can make fit in with thewelding torch's geometry.

[0009] In order to have the surfaces cleaned, the air stream that isnecessary to transport the abrasive and build up the required kineticenergy is divided into equal or non-equal sub-streams, depending on thenumber of jet nozzles employed and the size of the sections to becleaned. Based on the ratio selected, such subdivision is effected bychanging the pipe cross section or by combining several regulatingvalves.

[0010] By rotating the jet nozzle and/or directing the air flowout-of-center against the welding torch, an intensive cleaning of thedesired section is accomplished. Simultaneously making fit the nozzleoutlet in with the seam area will even increase the cleaning effect.

[0011] A further development of the invention involves the cold mixtureof abrasives to be blown in a pulsed mode. In case of more than one jetnozzle, such pulsation can be simultaneous or alternating.

[0012] The advantage of this invention is that using the cold jettechnology, in particular the employment of a mixture of CO₂ pelletswith air, the torches can be cleaned whatever their sizes or shapes are.The CO₂ pellets, or the carbon dioxide snow have an impact on limitedareas and cause them to cool down and become brittle so as to loosen thedirt whereat the air stream carries away the loosened dirt from insideand outside the welding torch.

[0013] Another advantage of this invention is that by using a cold jettechnology no direct contact is made with the welding torch which meansthat the welding torch's surface may not suffer any denudation or otherdamages.

[0014] An additional advantage of this invention is that several weldingtorches, being different in shape and size, may be cleaned in one singlecleaning station.

[0015] The invention will be described in greater detail by thefollowing two examples.

[0016]FIG. 1 configuration of a cleaning appliance

[0017]FIG. 2 configuration of a cleaning station for several weldingtorches with pulse-type mode of cleaning operation

EXAMPLE 1

[0018] Compressed air supplied by a compressor (1) (not shown in detail)is heated and dried in the treatment station (2) and then guided to thejet cleaning station (3). A contact maker (4) is connected with thewelding unit's working program. Approximately two seconds before end ofwelding program, the contact maker (4) switches on the driving motor (5)of the proportioning device (6). From the storage bin (8), the CO₂pellets (7) run into the metering disc (9) and by turning the same reachthe blasting station (10). In the blasting station (10), the CO₂ pellets(7) are metered to the stream of compressed air fed in through the line(11). The stream of compressed air (12) enriched with CO₂ pellets isguided to the jet nozzle (13). The jet nozzle (13) is fitted on anadapter (14) and, owing to the specific design of this adapter (14), isshifted out of its vertical position so that the stream of compressedair (12) is directed single-sided onto the area between the shieldinggas nozzle (15) and the electrode (16) of the welding torch (17). Therotary transmission (18) is driven by the motor (19) and allows the jetnozzle (13) to rotate covering the entire ring section (20) between theshielding gas nozzle (15) and the electrode (16). The CO₂ pellets (7)carried by the stream of compressed air (12) cause the deposited dirt(17) to cool down, and owing to the thermal tension built up betweenshielding gas nozzle (15) and dirt (17) the latter is chipping off fromthe shielding gas nozzle (15).

EXAMPLE 2

[0019] Compressed air supplied by the compressor (1) is heated and driedin the treatment station (2) and then fed through the line (21) into thestorage capacity (22), which has the non-return valve (23) fittedupstream. Downstream, the storage capacity (22) is equipped with thevalve (24) which is controlled by the contact maker (4). The drivingmotor (5) is triggered by the contact maker (4) and sets the meteringdisc (9) of the proportioning device (6) into a rotational motion. Aftera pre-selected time interval the valve (24) opens. In the blastingstation (10), the outflowing compressed air is loaded with the CO₂pellets (7). The stream of compressed air (12) enriched with CO₂ pelletsis fed into a distributor (25), inside which the stream of compressedair (12) is apportioned in accordance with the number of angled jetnozzles (26) employed.

[0020] The angled jet nozzles (26) are fitted on the adapter (14) wherethe rotary transmission (18) and the motor (19) set them into arotational motion. The substream of compressed air (27) enriched withCO₂ pellets is targeted out-of-center on a certain area of the ringsection (20) and onto the externals (28) of the shielding gas nozzle(15). Owing to the rotational motion of the rotary transmission (18) theangled jet nozzle (26) is guided so as to cover the entire ring section(20). List of reference numbers 1 compressor 2 treatment station 3 jetcleaning station 4 contact maker 5 driving motor 1 proportioning device2 CO₂ pellets 8 storage bin 9 metering disc 10 blasting station 11 line12 stream of compressed air 13 jet nozzle 14 adapter 15 shielding gasnozzle 16 electrode 17 welding torch 18 rotary transmission 19 motor 20ring section 21 line 22 storage capacity 23 non-return valve 24 valve 25distributor 26 angled jet nozzle 27 sub-stream of compressed air 28external area

1. Method for cleaning welding torches using a cold mixture of abrasivespreferably comprising CO₂ pellets and compressed air characterized inthat the stream of compressed air is directed by means of one or morejet nozzles single-sided, out-of-center and uniformly against a certainarea of the torch to be cleaned, at the same time rotating around thewelding torch's center axle so that a complete cleaning coverage of thearea to be cleaned is achieved.
 2. Method according to claim 1characterized in that the stream of compressed air is targeted withalternating intensity at intervals onto the area to be cleaned. 3.Method according to claim 1 and 2 characterized in that the stream ofcompressed air loaded with CO₂ pellets is apportioned according to thenumber of jet nozzles employed.
 4. Device for implementing the methodfor cleaning welding torches by means of a cold mixture of abrasivespreferably comprising CO₂ pellets and compressed air characterized inthat one or more jet nozzles, the outlet openings of which fit in, inshape and size, with the area to be cleaned, are positioned at an angleto the straight line drawn by the gearing axle and the welding torch,such angle being selected so as to fit in with the diameter of thesection to be cleaned, and where the jet nozzles are moving in acircular motion at the said angle around the said straight line whichallows the CO₂ pellets to uniformly cover the internal area of thewelding torch.
 5. Device for implementing the method for cleaningwelding torches by means of a cold mixture of abrasives preferablycomprising CO₂ pellets and compressed air characterized in that one ormore angled jet nozzles are moving in a circular motion around thestraight line drawn by the gearing axle and the welding torch, wherebythe stream of compressed air loaded with CO₂ pellets is targeted inparallel direction to the said straight line towards the welding torchso that both internal and external areas can be reached at the sametime.